Re: [PATCH 15/37] drm/i915: Export i915_request_skip()

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 29/06/2018 08:53, Chris Wilson wrote:
> In the next patch, we will want to start skipping requests on failing to
> complete their payloads. So export the utility function current used to
> make requests inoperable following a failed gpu reset.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem.c     | 25 +++----------------------
>   drivers/gpu/drm/i915/i915_request.c | 21 +++++++++++++++++++++
>   drivers/gpu/drm/i915/i915_request.h |  2 ++
>   3 files changed, 26 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index c13d5b78a02e..8ae293c75ae9 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3084,25 +3084,6 @@ int i915_gem_reset_prepare(struct drm_i915_private *dev_priv)
>   	return err;
>   }
>   
> -static void skip_request(struct i915_request *request)
> -{
> -	void *vaddr = request->ring->vaddr;
> -	u32 head;
> -
> -	/* As this request likely depends on state from the lost
> -	 * context, clear out all the user operations leaving the
> -	 * breadcrumb at the end (so we get the fence notifications).
> -	 */
> -	head = request->head;
> -	if (request->postfix < head) {
> -		memset(vaddr + head, 0, request->ring->size - head);
> -		head = 0;
> -	}
> -	memset(vaddr + head, 0, request->postfix - head);
> -
> -	dma_fence_set_error(&request->fence, -EIO);
> -}
> -
>   static void engine_skip_context(struct i915_request *request)
>   {
>   	struct intel_engine_cs *engine = request->engine;
> @@ -3117,10 +3098,10 @@ static void engine_skip_context(struct i915_request *request)
>   
>   	list_for_each_entry_continue(request, &engine->timeline.requests, link)
>   		if (request->gem_context == hung_ctx)
> -			skip_request(request);
> +			i915_request_skip(request, -EIO);
>   
>   	list_for_each_entry(request, &timeline->requests, link)
> -		skip_request(request);
> +		i915_request_skip(request, -EIO);
>   
>   	spin_unlock(&timeline->lock);
>   	spin_unlock_irqrestore(&engine->timeline.lock, flags);
> @@ -3163,7 +3144,7 @@ i915_gem_reset_request(struct intel_engine_cs *engine,
>   
>   	if (stalled) {
>   		i915_gem_context_mark_guilty(request->gem_context);
> -		skip_request(request);
> +		i915_request_skip(request, -EIO);
>   
>   		/* If this context is now banned, skip all pending requests. */
>   		if (i915_gem_context_is_banned(request->gem_context))
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index d618e7127e88..51f28786b0e4 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -962,6 +962,27 @@ i915_request_await_object(struct i915_request *to,
>   	return ret;
>   }
>   
> +void i915_request_skip(struct i915_request *rq, int error)
> +{
> +	void *vaddr = rq->ring->vaddr;
> +	u32 head;
> +
> +	GEM_BUG_ON(!IS_ERR_VALUE((long)error));

Why not simply error >= 0 ? Error is an integer in this function, and in 
dma_fence_set_error. In fact, looking at dma_fence_set_error it is 
already checking for valid errno.

> +	dma_fence_set_error(&rq->fence, error);

Was at the end before code movement.

> +
> +	/*
> +	 * As this request likely depends on state from the lost
> +	 * context, clear out all the user operations leaving the
> +	 * breadcrumb at the end (so we get the fence notifications).
> +	 */
> +	head = rq->infix;

Original assignment is head = rq->head. Looks to be the same but why 
change it in code movement patch?

> +	if (rq->postfix < head) {
> +		memset(vaddr + head, 0, rq->ring->size - head);
> +		head = 0;
> +	}
> +	memset(vaddr + head, 0, rq->postfix - head);
> +}
> +
>   /*
>    * NB: This function is not allowed to fail. Doing so would mean the the
>    * request is not being tracked for completion but the work itself is
> diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> index 7ee220ded9c9..a355a081485f 100644
> --- a/drivers/gpu/drm/i915/i915_request.h
> +++ b/drivers/gpu/drm/i915/i915_request.h
> @@ -258,6 +258,8 @@ void i915_request_add(struct i915_request *rq);
>   void __i915_request_submit(struct i915_request *request);
>   void i915_request_submit(struct i915_request *request);
>   
> +void i915_request_skip(struct i915_request *request, int error);
> +
>   void __i915_request_unsubmit(struct i915_request *request);
>   void i915_request_unsubmit(struct i915_request *request);
>   
> 

Regards,

Tvrtko
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